Refrigerating apparatus



2%, W32. D. E. MACCABEE 398423529 REFRIGERATING APPARATUS Filed March 61, 1930 INVENTOR lti Patented Jan. 26, 1932 UNITED STATES PATENT OFFICE DAVID E. MACCABEE, F DAYTON, OHIO, AS SIGNOR TO FRIGIDAIRE CORPORATION, OF DAYTON, OHIG, A CORPORATION OF DELAWARE REFRIGERATING APPARATUS Application filed March 31, 1930. Serial No. 440,493.

This invention relates to refrigerating apparatus and particularly to soda fountains and similar devices in which various commodities of different characters are maintained at different temperatures.

One of the objects of the invention is to provide a simple and economical refrigerating apparatus particularly adapted to soda fountains.

Another object of the invention is to provide an improved and simplified arrangement for maintaining a number of different cornpartments at diflerent temperatures by means of a single refrigerating system.

More specifically it is an object of the 1nvention to operate a plurality of evaporating elements in series and to provide an improved arrangement for controlling the amount of refrigerant which is evaporated in each successive evaporator of the series.

Further objects and advantages of the present invention will be apparent from the following description, referencebeing had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a diagram of a refrigerating system embodying the invention; and

' Fig. 2 is a vertical longitudinal section of a portion of an evaporator.

llt is usual to rovide soda fountains with a compartment or storing ice cream which should be kept at a temperature of 7 F. or less, a compartment for storing and cooling water ondraft which should be maintained at a temperature between 35 and 40 and a compartment for containers of fountain syrups, fruit juices and the like, commonly called a syrup rail, which should be maintained at a temperature between 35 and 55 F.

Une of the systems heretofore used for re frigerating soda fountains includes a con densing element having a compressor 10 operated by an electric motor 12 for withdrawing gaseous refrigerant from a vapor return line 14 compressing the refrigerant so that it will be liquefied in a condenser 16 from which it flows to a receiver or reservoir 18.

Liquid refrigerant is supplied from the reservoir by a conduit 20 to an evaporator 22 called the water coil located in a compartment 24 and usually immersed in sweet water for cooling circulating drinking water. From the evaporator 22 liquid refrigerant is led by a conduit 26 to a second evaporator 28 called the ice cream coil located in a compartment 30 and usually immersed in brine for cooling ice cream. The conduit 26 includes a portion 32 disposed in a compartment 34 usually called a syrup rail, the con d'uit 32 acting as an evaporator to cool fountain syrups. The vapor return conduit 14 has an unobstructed connection with a conduit 36 by which gaseous refrigerant is withdrawn from the evaporator 28. The evaporator 22 is connected to the conduit 14 by a vapor return conduit 38 through a pressure regulating valve 40 which may be constructed for example as shown in the application of Ernest Dickey, Serial No. 753,048 filed December 1, 1924. The motor 12 ordinarily runs intermittently being started and stopped automatically in response to the condition of the refrigerating system by a pressure-1e sponsive switch 42 connected to the vapor return conduit 14.

Each of the evaporators is of the flooded type in which the pressure of the refrigerant bears a direct relation to the temperature of the evaporator and each includes a header or reservoir for liquid refrigerant 50, which forms a gas and liquid separating chamber, to which liquid refrigerant is admitted from an inlet connection 52 through the orifice 53 under the control'of a needle valve 54 operated by a float 56 to maintain a constant level of refrigerant in the reservoir. Gaseous refrigerant is withdrawn from the upper part of the reservoir by conduit 36 or 38 through a vapor connection 58 and a tube 60 having its inlet or open end 62 disposed above the maximum level of liquid in the chamber 50. This tube has an opening 64 in its side wall below the level of-the mouth 62 which opening permitsthe draining of oil, collecting on top of the liquid. refrigerant back to the coinpressor through the vapor return conduit. Depending from the chamber are any suit- 28 are identical. In addition to the features" enumerated above the evaporator 22 is pro vided with a fitting 7 through which the vapor connection 58 communicates with the tube 60 and which is provided with a conduit connection 7 2 communicating with a small tube 74 but not communicating with the liquid passes into the vapor conduit 60. The tube 74 is passedthrough the tube and extends into the reservoir 50 below the level of liquid refrigerant. The conduit 26 leads from the connection 72 to the liquid inlet connection 52 of the evaporator 28 and forms the sole source of supply of refrigerant to that evaporator.

When the compressor is operating, gaseous refrigerant is withdrawn from both the evaporators, the pressure regulating device 40 operating to maintain any desired difference in pressure between the evaporators 22 and 28. The switch 42 may be set to start the compressor when the pressure in the vapor return line is high, for example'5 pounds per square inch gauge and to pressor when the pressure has reached the predetermined low value, for example a vacuum of 18 inches of mercury. The pressure regulating device restricts or prevents communication between the vapor conduit 38 and the vapor conduit 14 whenever the pressure in the vapor conduit 38 reaches a predetermined low value, for example 2pounds per square inch gauge. maintains a suitable temperature, for example 40 in the water compartment, and a lower temperature, for example 0 or below in the ice cream compartment.

It will be appreciated that due to the difference in pressure between the water coil and ice cream coil, liquid refrigerant will be forced from the chamber 50 of the water coil through thesmall tube 7 4 and through the conduit 26 to the inlet 52 of the ice cream coil, and whenever the float valve 56 of the ice cream coil is open liquid refrigerant will be admitted to that coil.

Theoretically1 erant passing t rough the conduit 26 is evaporated in the conduit 32 to provide refrigeration for the syrup rail, and a part of the evaporator 28 to be vaporized there to provide refrigeration for the ice cream compartment. In practice considerable operating 'diflicult has been encountered due to the fact t at not enough refrigerant in liquid form reaches the ice cream coil. This has'two undesirable results, first, a suflicient amount of refrigeration is not provided for the ice cream compartment and second, due to the fact that liquid stop the comcoil this pressure'may never be This arrangement a part of the liquid refriglevel in the chamber 50 may never be high the refrigerant evaporates leaving the oil in the chamber 50, which eventually becomes filled with.oil to the exclusion of refrigerant, or as is known-in the trade, oil-logged.

enough to drain oil through the opening 60, q

My investigations lead me to believe that this starving of the ice cream coil is due to two causes. First, when the compressor starts the pressures in the two evaporators are practically equal since the pressure regulating device 40 never completely closes and the pressures equalize during the idle periods of the compressor. Therefore the difl'erence in pressure between the two evaporators which is required to force a sufficient quantity of liquid into the evaporator 28 is not attained until after a considerable period of operation of the compressor. The pressure differential therefore varies from zero at the beginning of an operating period to the maximum at the end of an operating period.

During this time the quantity of liquid supplied to the evaporator 28 may be insuificient to provide for the refrigerating demand on that evaporator. Second, on starting the apparatus for the first time, or after a period of shut-down when the conduit 32 has bec ome.

uite warm, the liquid which is initially Iorced into the conduit 32 flashes into vapor and builds up a pressure sufiicient to prevent the flow of liquid from the evaporator 22 to the evaporator 28. Since the only communication between the conduit 32 and the compressor for the withdrawal of vapor is the small float valve "orifice 53 in the ice cream reduced to a sufficiently low value to supply liquid to the evaporator 28. Y Moreover the flashing of refrigerant into-vapor in the conduit 32 may blow back liquid refrigerant through the connection 7 4 and thus empty the tube of liquid. My invention overcomes the objections to the above described system by means of a receiver or reservoir 80 between the water coil and the syru rail and above the level of the ice cream coi This reservoir has its inlet connection 82 at the top and its outlet connection 84 at the bottom so that any liq- .uid reaching the reservoir cannotbe blown back as liquid into the water coil but can drain or be forced to the ice cream coil. If desired the reservoir 80 may be insulated'in order that li uid refrigerant admitted thereto ma not e flashed into vapor.- Preferably t e portion 86 of the conduit 26 between the water coil and the reservoir is also insulated and is provided with a check valve 88 which prevents any return flow of refrigerant or the transmission of any pressure from the syrup rail to the water coil.

. 80 because refrigerant can flow through the a portion exposed to a source of heat in said connection 74 faster than through the float valve of the ice cream coil. During this period any desired quantity of liquid reirlgerant may be stored in the reservoir 80 which is suitably proportioned for this purpose, and this supply of liquid may drain by gravity to the ice cream coil Whenever the float valve is open, whether or not the compressor is operating. This supplies the ice cream coil with the requisite quantity of liquid refrigerant.

While the form of embodiment of the invention as herein disclosed, constitutes a preterred form, it is to be understood that other forms might be adopted,'all coming Within the scope of the claims which follow.

What is claimed is as follows:

1. Refrigerating apparatus comprising in combination a relatively high pressure evaporator including a reservoir for liquid reatrigerant, a relatively low pressure evaporator including a reservoir for liquid refrigerant, and a conduit for conducting liquid refrigerant from the high pressure evaporator to the low pressure evaporator, the conduit including an insulated liquid reservoir above the level of the low pressure evaporator, and a portion exposed to a source of heat.

2. Refrigerating apparatus comprising in combination a relatively high pressure evaporator including a reservoir for liquid refrigerant, a relatively low pressure evaporator and a conduit for conducting liquid refrigerant from the high pressure evaporator to the low pressure evaporator, the conduit including an insulated liquid reservoir above the level of the low pressure evaporator, and a portion exposed to a source of heat.

3. Refrigerating apparatus comprising in combination a relatively high pressure evaporator including a reservoir for liquid refrigerant, a relatively low pressure evaporator, and a conduit for conducting liquid refrigerant from the high pressure evaporator to the low pressure evaporator and for cooling a compartment above the low pressure evaporator, the conduit including an insulated liquid reservoir in said compartment above the level of the low pressure evaporator, and a portion exposed to a source of heat in said compartment above the level of the low pressure-evaporator. I

4. Refrigerating apparatus comprising in combination a relatively high pressure evaporator including a reservoir for liquid refrigerant, a relatively low pressure evaporator, and a; conduit for conducting liquid refrigerant from the high pressure eva orator to the low pressure evaporator and or cooling a compartment above the low pressure evaporator, the conduit including an insulated liquid reservoir in said compartment above the level of the low pressure evaporator, and

compartment above the level of the low pressure evaporator and means in the conduit for preventing the flow of liquid to the high pressure eva orator.

5. Re rigerating apparatus comprising in combination a relative y high pressure evaporator having a gas and liquid separating chamber, a relatively low pressure evapora tor, a liquid inlet to said high pressure evaporator, and means res onsive to the quantity of liquid in said cham er for controlling the passage of liquid thereto, a conduit leading below the level of liquid in the high pressure evaporator to the inlet of the low pressure evaporator, a liquid refrigerant reservoir intercon'necting said conduit above said high pressure evaporator, said reservoir being adapted to receive its liquid refrigerant only due to the diiierence in pressures in said evaporators, said reservoir having a greater cross sectional area than said conduit, and means for controlling the admission of liquid to said lowipressure evaporator, the apparatus being arranged to supply liquid refrigerant to said reservoir when the pressure differential is high to thereby provide for the supply of liquid to the low pressure evaporator when the pressure difierential is low.

In testimony whereof I hereto aflix my signature.

' DAVID E. MACCABEE. 

